final/train.py

import os
import pandas as pd
import numpy as np
import torch
from torch import nn
from sklearn.metrics import accuracy_score, f1_score, precision_score, recall_score
from sklearn.utils.class_weight import compute_class_weight
from datasets import Dataset
from transformers import (
    AutoTokenizer,
    AutoModelForSequenceClassification,
    TrainingArguments,
    Trainer,
    EvalPrediction
)
import optuna

# --- 1. 网络与缓存配置 (自动修正路径版) ---
os.environ['HF_HUB_OFFLINE'] = '1' 

# 定义基础路径
base_path = "/root/autodl-tmp/huggingface_cache/models--roberta-base"

# 自动探测真实的快照路径
MODEL_NAME_OR_PATH = base_path
if os.path.exists(os.path.join(base_path, "snapshots")):
    snap_path = os.path.join(base_path, "snapshots")
    snapshots = [d for d in os.listdir(snap_path) if os.path.isdir(os.path.join(snap_path, d))]
    if snapshots:
        # 使用找到的第一个快照文件夹
        MODEL_NAME_OR_PATH = os.path.join(snap_path, snapshots[0])
        print(f"✅ 成功定位模型真实路径: {MODEL_NAME_OR_PATH}")
    else:
        print("⚠️ 警告: snapshots 文件夹为空，尝试使用根目录")
else:
    print(f"ℹ️ 未发现 snapshots 结构，尝试使用路径: {MODEL_NAME_OR_PATH}")

# --- 2. 定义文件路径 ---
TRAIN_FILE_PATH = "/tmp/home/wzh/file/train_data.csv"
VALID_FILE_PATH = "/tmp/home/wzh/file/val_data.csv" 

# --- 3. 加载数据 ---
print(f"加载训练集: {TRAIN_FILE_PATH}")
train_df = pd.read_csv(TRAIN_FILE_PATH)
print(f"加载验证集: {VALID_FILE_PATH}")
eval_df = pd.read_csv(VALID_FILE_PATH)

label_map = {"real": 0, "fake": 1}
train_df['label'] = train_df['label'].map(label_map)
eval_df['label'] = eval_df['label'].map(label_map)

# --- 4. 计算类别权重 ---
print("\n正在计算类别权重...")
train_labels = np.array(train_df["label"])
class_weights = compute_class_weight(class_weight='balanced', classes=np.unique(train_labels), y=train_labels)
device = "cuda" if torch.cuda.is_available() else "cpu"
class_weights_tensor = torch.tensor(class_weights, dtype=torch.float).to(device)
print(f"计算出的类别权重: {class_weights}")

# --- 5. 创建Dataset与分词 ---
train_dataset = Dataset.from_pandas(train_df)
eval_dataset = Dataset.from_pandas(eval_df)

print(f"\n正在加载本地模型: {MODEL_NAME_OR_PATH} ...")
tokenizer = AutoTokenizer.from_pretrained(MODEL_NAME_OR_PATH)

def tokenize_function(examples):
    return tokenizer(examples["text"], padding="max_length", truncation=True, max_length=512)

tokenized_train_dataset = train_dataset.map(tokenize_function, batched=True)
tokenized_eval_dataset = eval_dataset.map(tokenize_function, batched=True)

columns_to_remove = ["id", "text"]
if "__index_level_0__" in train_df.columns:
    columns_to_remove.append("__index_level_0__")

tokenized_train_dataset = tokenized_train_dataset.remove_columns(columns_to_remove)
tokenized_eval_dataset = tokenized_eval_dataset.remove_columns(columns_to_remove)
tokenized_train_dataset = tokenized_train_dataset.rename_column("label", "labels")
tokenized_eval_dataset = tokenized_eval_dataset.rename_column("label", "labels")

# --- 6. 自定义Trainer (应用类别权重) ---
class CustomTrainer(Trainer):
    def compute_loss(self, model, inputs, return_outputs=False, **kwargs):
        labels = inputs.pop("labels")
        outputs = model(**inputs)
        logits = outputs.get("logits")
        loss_fct = nn.CrossEntropyLoss(weight=class_weights_tensor)
        loss = loss_fct(logits.view(-1, self.model.config.num_labels), labels.view(-1))
        return (loss, outputs) if return_outputs else loss

# --- 7. 配置超参数搜索 ---
id2label = {0: "real", 1: "fake"}
label2id = {"real": 0, "fake": 1}

def model_init(trial):
    return AutoModelForSequenceClassification.from_pretrained(
        MODEL_NAME_OR_PATH,
        num_labels=2,
        id2label=id2label,
        label2id=label2id,
    )

# ！！！修复点 1：这里返回完整的字典，而不是 float ！！！
def compute_metrics_macro(p: EvalPrediction):
    labels = p.label_ids
    preds = np.argmax(p.predictions, axis=1)
    
    f1_macro = f1_score(labels, preds, average='macro', zero_division=0)
    acc = accuracy_score(labels, preds)
    precision_macro = precision_score(labels, preds, average='macro', zero_division=0)
    recall_macro = recall_score(labels, preds, average='macro', zero_division=0)
    
    return {
        "accuracy": acc, 
        "f1_macro": f1_macro, 
        "precision_macro": precision_macro, 
        "recall_macro": recall_macro
    }

# ！！！修复点 2：专门定义一个函数给Optuna提取目标值 ！！！
def compute_objective(metrics):
    # Trainer 会自动给指标加上 'eval_' 前缀
    return metrics['eval_f1_macro']

training_args = TrainingArguments(
    output_dir="./results_hyper_search_MACRO",
    per_device_train_batch_size=16, # 保持16防止爆显存
    per_device_eval_batch_size=16,
    weight_decay=0.01,
    
    eval_strategy="steps",
    eval_steps=1000, 
    save_strategy="steps", # 保持同步
    save_steps=1000,
    logging_strategy="steps",
    logging_steps=1000,
    
    load_best_model_at_end=True,
    metric_for_best_model="f1_macro", # 对应 compute_metrics 返回字典里的 key
    greater_is_better=True,
    save_total_limit=1,
)

trainer = CustomTrainer(
    model=None,
    args=training_args,
    model_init=model_init,
    train_dataset=tokenized_train_dataset,
    eval_dataset=tokenized_eval_dataset,
    tokenizer=tokenizer,
    compute_metrics=compute_metrics_macro, # ！！！这里传入返回字典的函数！！！
)

# --- 8. 开始自动超参数搜索 ---
print("\n" + "="*50)
print("🚀 开始自动超参数搜索 (目标: 最大化 Macro-F1)...")
print("="*50)

best_run = trainer.hyperparameter_search(
    direction="maximize", 
    n_trials=10, # 尝试10次
    compute_objective=compute_objective, # ！！！这里告诉Optuna怎么提取分数！！！
    backend="optuna"
)

print("\n" + "="*50)
print("🎉 超参数搜索完成！")
print("="*50)
print(f"最佳 Macro-F1: {best_run.objective:.4f}")
print("最佳参数组合:", best_run.hyperparameters)

# --- 9. 使用最佳参数进行最终训练 ---
print("\n" + "="*50)
print("🚀 使用最佳参数进行最终训练...")
print("="*50)

for k, v in best_run.hyperparameters.items():
    setattr(training_args, k, v)
training_args.output_dir = "./results_final_best_MACRO"
training_args.logging_steps = 200 

# 重新创建Trainer
trainer = CustomTrainer(
    model_init=model_init,
    args=training_args,
    train_dataset=tokenized_train_dataset,
    eval_dataset=tokenized_eval_dataset,
    compute_metrics=compute_metrics_macro,
)

trainer.train()
print("\n" + "="*50)
print("🎉 最终训练完成！")
print("="*50)

# --- 10. 保存与最终报告 ---
final_model_path = "./final_model_best_macro"
trainer.save_model(final_model_path)
tokenizer.save_pretrained(final_model_path)
print(f"\n最终最优模型已保存至: {final_model_path}")

print("\n--- 最终成绩单 (验证集) ---")
final_metrics = trainer.evaluate()

for key, value in final_metrics.items():
    if key.startswith("eval_"):
        key = key[5:]
    if isinstance(value, float):
        print(f"  - {key}: {value:.4f}")
    else:
        print(f"  - {key}: {value}")